That noisy traffic outside your home could do more than disrupt your sleep. It may also raise your risk of developing tinnitus [tin-nuh-tuhs], a chronic ringing or other noise in the ears.

Researchers at the University of Southern Denmark studied data from 3.5 million people, finding that the risk of tinnitus grew along with traffic noise. It is the first time scientists have found a correlation between hearing issues and residential traffic noise.

In addition to identifying more than 40,000 cases of tinnitus, they made a broader connection: For every 10 decibels that sound increased in Danish homes, there was a 6% increase in the risk of tinnitus. For example, 10 decibels are about the sound level a human produces when breathing, while a typical washing machine generates 70 decibels.

The researchers also noted that traffic noise can be part of a vicious, unending cycle. Traffic noise can cause stress and sleep disruptions, which can cause tinnitus to become even worse.

So how much noise is too much? In Denmark, the guidance level for harmful traffic noise indoors is 58 decibels. In the United States, it’s 55 decibels, or about the sound level of a normal conversation.

Solutions can come in many forms, although some are easier than others. Sleeping in a room farthest from the road is the simplest option. Installing sound-reducing windows is another strategy.

In some places, government has gotten involved. Noise-buffering barriers can be placed along roads. In Germany, speed limits have been lowered in some places at night.

When it comes to avoiding tinnitus, a little less noise in your home can make a big difference.